Process of making tetra-nitro-dianthrone



Patented 9, 1928. v v

UNITED STATES snnrnor-n s-rs or ELBERFELD,

conromrron, or NEW YORK,

PROCESS OF MAKING- TlgTRA-NITRO-DIANTHRONE.

li'o Drawing. Application My invention consits in tetra-nitro-dianthranol and in the process of making the same.

Dianthrone of the formula;

- con @011 CIH Goon his always been considered as an exceedingly stable compound, and only very few reac- 415 tions are known by which this dianthrone can be transformed into other compounds. It is, for instance, stated by H. Meyer (Wiener Monatschefte fiir Chemie vol. 30, page 165) that it canbe easily purified by recrystallization from concentrated mtr c acid.

I have now found that if dianthrone is treated in concentrated sulfuric acid with nitric acid, a tetra-nitro-dianthrone isobtained in which the nitro tachedto beta positions. .T is tetra-nitrodianthrone is obtained as colorless crystals which are diflicultly soluble in concentrated sulfuric acid. It is hardly attacked by acid reducing agents. 'Boiled up in pyridine a green solution is obtained, which becomes quickly brown. On cooling dark needles are separated, which are supposed to. be the pyridine salt of the tera-nitro-dianthranol. The tetra-nitro-dianthrone is intended to be used as intermediate product in the manufacture of dyestuffs and other compounds.

The following example will further illus: trate my invention:

Example-5O grams powdered dianthrone are withgood stirring introduced at a tem-. perature of fromto G. into .190 cc. of a mixture of strong nitric and sulfuric acids containing 0.2 .grams nitric acid per cubic centimeter. I

The dianthrone is at first dissolved with yglalow color but even before all of it has n introduced, colorless crystals start to separate, the amount of which gradually increases. After all of the dianthrone has been introduced, the reaction is allowed to stir for another four hours, and is thenfiltered over asbestos or lass wool, washed at first with a 60 B. sul uric acid and then ups are atv 1,686,992 PATENT OFFICE.

GERIANY, \ASSIGNOR T0 GRASSELLI DYESTUFF N. Yf, A. CORPORATION OF DELAWARE.

filed June 2a, 1920, semi No. 119,200, and in Germany June as, 1925.

to neutrality with hot water. The yield is excellent, being between 90 and 92% of theory. The tetra-nitro-dianthrone is obtained in this way as colorless crystals. It b is very difiicultly soluble in concentrated sulfuric acid and in most or anic solvents. 60 Acid reduction agents har y attack it, whereas through alkaline agents it can be reduced to a tetra-amido-dianthrone. Boiled up with pyridine or weak alkaline agents, such as aniline or weak aqueous alcoholic caustic, salts of the tetra-nitro-diantranol are obtained, which may be represented by the formula:

E N0 L N0:

N 0 NO:

in which X is a basic radicle.

I claim: v

1. The process of making tetra-nitrodianthrone which comprises reacting dianthrone with a nitrating agent in the presence of concentrated sulfuric acid.

2. The process-of making tetra-nitrodianthrone which consists in treating dianthrone with a mixture of strong nitric and sulfuric acids.

3. The process of making tetra-nitror dianthrone which consists in treating dianthrone with a mixture of strong nitric and sulfuric acids at temperatures below room temperature.

'4. As a new compound, tetra-nitro-dianthrone in which the nitro groups are attached in a beta position, which is obtained 10o in-the form of colorless crystals diflicultly BERTHOLD- STEIN.- 

